Execution dying while scrambling serial debugger

I have some code that calls an object in a new cog, but calling the cog causes the rest of the code in the original cog to halt execution. When I use the serial debugger to try and debug, I get a bunch of nonsense in the output. Here is the code for the calling cog:

con
  _CLKMODE = XTAL1 + PLL16X
  _XINFREQ = 5_000_000
obj
  sinsynth : "sintabsynth"
  sawsynth : "sawtabsynth"
  trisynth : "triangletabsynth"
  squaresynth:"squaretabsynth"
  keyReader:"keyReader"
  DDS      : "DDS_PASM"
  Debug    : "FullDuplexSerial"
var      
  byte cog1   
  long cogStack1[50]  
  long playFreqs[5]
  long playPress[5]
  byte t1
pub main
 
  Debug.start(31,30,0,57600)
  waitcnt(clkfreq*4 + cnt)
  Debug.str(string("trying strings", $D))   
  cog1 := cognew(keyReader.Main(@playFreqs, @playPress), @cogStack1) + 1   
  repeat
   t1 := 0
   repeat while t1 < 6
    Debug.dec(playFreqs[t1])
    t1++
   waitcnt(clkfreq/6 + cnt)  

and here is the code that is causing the problem, which is the code that is loaded in the cog called by the code above:

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
 
  threshold = 300 
OBJ                         
  AD_DRVR : "MCP3208_DRIVER"
  Debug    : "FullDuplexSerial" 
VAR  'options: long, word or byte 
  byte keyRef
  byte playRef
  byte lowPlayKey    'lowest playset key pointer
  byte t1
  byte t2
  byte t3
  byte t4
  byte t5                            
  byte highestKeyIndex          
  byte adc     
  long keyReadings[24]      
  long cogStack[10]
  byte cog  
  'long highestKeyReading
PUB Main(playFreqs, playPress)
  Debug.start(31,30,0,57600)
  waitcnt(clkfreq*4 + cnt)
  Debug.str(string("trying strings2", $D))                       
  cog := cognew(GetKeyReadings, @cogStack) + 1
  repeat
    keyRef := 0
    repeat while keyRef < 25                        'iterate through key readings
      if keyReadings[keyRef] > threshold             'check if above the threshold
        playref := 0
        t1 := 0
        repeat while playRef < 6                   'now determine if key is already in playset
          if long[@Freqs][keyRef] == long[playFreqs][playRef]
             t1 := 1
             quit
          playRef++ 
        if t1 == 1                                 'if key is already in the playset....
          long[playPress][playRef] := keyReadings[keyRef]  'then update the pressure
        else                                       'if key is not already in the playset
          playRef := 0
          t1 := 0
          repeat while playRef < 6                'determine if there are 6 keys already in the playset
            if long[playFreqs][playRef] == 0
              t1 := 1
              quit
            playRef++
        if t1 == 1                               'if there aren't 6 keys already in the playset..
          long[playFreqs][playRef] := long[@Freqs][keyRef] 'then add the key freq and pressure to the playset
          long[playPress][playRef] := keyReadings[keyRef]  
        else                                     'if there are 6 keys already in the playset...
          playRef := 0                           'then find lowest key in the playset  
          t1 := 0
          t2 := 4095                                      
          repeat while playRef < 6
            t1 := long[playPress][playRef] 
            if t1 < t2
              t2 := t1
              't5 := playRef
            playRef++
          long[playFreqs][t2] := long[@Freqs][keyRef] 't2 now has the lowest key, so replace it using keyRef
          long[playPress][t2] := keyReadings[keyRef]     
      else                                         'keyReading is not above threshold
        playref := 0
        t1 := 0
        repeat while playRef < 6                   'determine if key is already in playset
          if long[@Freqs][keyRef] == long[playFreqs][playRef]
             t1 := 1
             quit
          playRef++
        if t1 == 1                                  'if it's in the playset
           long[playPress][playRef] := 0           'then delete it
           long[playPress][playRef] := 0  
      keyRef++
 
 
 
PUB GetKeyReadings                                
  repeat        
    t3 := 0 'keeps track of the key we're reading
    adc := 0 'keeps track of the adc IC we're reading from
    repeat while adc =< 3
      if adc == 0
        AD_DRVR.start(21,20,19,0)
      elseif adc == 1
        AD_DRVR.start(18,17,16,0)
      elseif adc == 2
        AD_DRVR.start(13,14,15,0)
      elseif adc == 3
        AD_DRVR.start(10,11,12,0)
      t4 := 0 'keeps track of the adc channel we're reading from
      repeat while t4=<7
        if (adc==1 AND t4>3) OR (adc==3 AND t4>4)
          quit
        keyReadings[t3] := AD_DRVR.in(t4)
        t4++
        t3++      
      adc++                   
DAT
'Define the frequencies for the middle octave                                                                 
Freqs   long 523,494,466,440,415,392,369,349,330,311,294,277,262,247,233,220,208,196,185,175,165,156,147,139,131

I tried making cogStack1's length higher in the calling code, but that didn't change anything. Any suggestions? It may be something obvious, I've only been propelling for a couple months now. Thanks for the help.